Apparatus for aligning a reflector and a light source



Dec. 24, 1968 'r. A. HOFFMANN 3,413,052

APPARATUS FOR ALIGNING A REFLECTOR AND A LIGHT SOURCE Original FiledDec. 5. 1961 5 Sheets-Sheet l 64 v 63 4 0 mmvron.

THOMAS A. HOFFMANN. {Ki/BY 3 5, $11.?

Dec. 24, 1968 T. A. HOFFMANN APPARATUS FOR ALIGNING A REFLECTOR AND ALIGHT SOURCE S Sheets-Sheet 2 Original Filed Dec. 5, 1961 V FIG. l2.

FIQ. l0.

INVENTOR.

THOMAS A. HOFFMANN.

Dec. 24, 1968 TQA. HOFFMANN I 3,418,052

APPARATUS FOR ALIGNING A REFLECTOR AND A LIGHT SOURCE Original FiledDec. 5. 1961 5 Sheets-Sheet 5- l4. FIG. l6.

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9. gfbbibb United States Patent 3,418,052 APPARATUS FOR ALIGNING AREFLECTOR AND A LIGHT SOURCE Thomas A. Hoifmann, Morris Plains, N.J.,assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., acorporation of Pennsylvania Original application Dec. 5, 1961, Ser. No.157,217, now Patent No. 3,194,626. Divided and this application Nov. 16,1964, Ser. No. 411,260

6 Claims. (Cl. 356-123) ABSTRACT OF THE DISCLOSURE An apparatus fordetermining the position of a component, such as a filament, relative toa curved reflector to which it is attached and detecting deviations, ifany, from a given alignment. The reflector-filament assembly is lockedin predetermined position of a chassis which carries a screen and alight source that are so oriented with respect to each other and theassembly that a shadow of the filament is projected by the reflectoronto the screen when the light source is energized. The position of theprojected shadow relative to a reference mark on the screen indicatesthe degree of misalignment, if any, between the reflector and filament.

This application is a division of copending application Serial No.157,217, filed December 5, 1961, now US. Patent No. 3,194,626.

This invention relates to optical systems and, more particularly, to animproved apparatus for accurately aligning the light source andreflector components of an electric projection lamp.

In the manufacture of certain types of devices it is frequentlynecessary that an element be precisely located with respect to a curvedreflector surface. In the case of electric projection lamps havingintegral reflectors, for example, it is essential that the filament belocated in predetermined relation with respect to the focal point of thereflector in order to obtain the desired beam pattern and intensity. Dueto the construction of such lamps and the precision required, it hasbeen found that the alignment of the filament and reflector must be donebefore the envelope is sealed and exhausted. The filament accordinglycannot be lighted during the prefocusing operation, as is done in thecase of other lamp types, since it would rapidly oxidize in theatmosphere and be ruined. Because of this restriction various types ofoptical measuring devices are used to locate the focal point of thereflector before the envelope is sealed so that the filament can bemounted on its supporting structure in the desired position relative tothe focal point. This method of prefocusing leaves much to be desiredsince it is a time-consuming operation and requires complicated andexpensive measuring and filamentmounting apparatus.

It is accordingly the general object of this invention to provide asimpler and less expensive means for accurately positioning an elementwith respect to a reflector surface.

Another and more specific object is the provision of apparatus that willpermit the filament and reflector components of an electric lamp to beprefocused on a production line basis without energizing the filament.

Another object is the provision of an inexpensive rugged device that canbe easily operated and will quickly check the alignment of an elementand a curved reflector surface and facilitate the correction of anymisalignment.

The foregoing objects, and others which will become apparent to thoseskilled in the art as the description 3,418,052 Patented Dec. 24, 1968proceeds, are achieved in accordance with this invention by utilizingthe curved reflector surface itself as the mirror portion of an opticalsystem for checking the alignment of the deenergized filament or otherelement. Briefly, a beam of radiant energy is aimed at the element froma predetermined angle and the position of the element relative to thereflector surface is checked by observing the orientation of thereflected shadow of the element on a screen that detects the type ofradiant energy employed. In the case of a reflector having a focalpoint, two beams are preferably aimed at the reflector at angles suchthat the beam axes intersect in the region of the focal point so thattwo reflected shadows of the element appear on the screen. By observingthe positions of the shadows relative to reference marks on the screeneven minute rnisalignments can be very readily detected and corrected.In the case of a reflector and a filament, light beams and a frostedglass screen are employed.

Utilizing the aforesaid principle, suitable light sources and a screenare mounted on a common base or support together with a jig for holdingthe reflector to provide a prefocusing apparatus that is compact andvery simple to operate.

A better understanding of the invention will be obtained by referring tothe accompanying drawings, wherein:

FIGURE 1 is a perspective view of an incandescent projection lamp thatcontains an integral reflector and is representative of the type of lampwith which the invention is concerned, a part of the lamp envelope beingbroken away to reveal the lamp mount;

FIG. 2 is a perspective view of the integral reflectorfilament assemblyemployed in the lamp shown in FIG. 1;

FIG. 3 is a perspective view of prefocusing apparatus embodying theinvention;

FIG. 4 is a fragmentary plan view of the apparatus shown in FIG. 3, theholding jig portion whereof and the inserted reflector-filament assemblyand screen being shown in cross section, the view being taken along theline IV-IV of FIG. 3, in the direction of the arrows;

FIG. 5 is a fragmentary cross-sectional view through the movable jaw ofthe holding jig taken along the line V-V of FIG. 4, in the direction ofthe arrows;

FIGS. 6, 8, 10 and 12 are diagrammatic views illustrating the differentoptical effects obtained with various filament locations in the case ofan ellipsoidal reflector;

FIGS. 7, 9, 11 and 13 are fragmentary elevational views of the screenillustrating the orientation of the reflected shadows of the filament onthe screen produced by the various situations depicted in FIGS. 6, 8, l0and 12, respectively; and

FIGS. 14 to 21 are illustrations corresponding to FIGS. 6 through 13 butshow various alignments and resultant screen patterns that would beobserved in the case of a parabolic reflector.

While the present invention can be advantageously employed in themanufacture of various types of devices that include a reflector elementwhich must be precisely oriented with respect to another component, itis particularly adapted for use in conjunction with electric lampshaving an integral reflector and a concentrated light source, such asincandescent projection lamps, and the invention has accordingly been Soillustrated and will be 50 described.

With specific reference to the drawings, in FIG. 1 there is shown anincandescent projection lamp 22 representative of the type ofintegral-reflector lamp that presents the troublesome prefocusingproblems with which this invention deals. As is well known, such lampsconsist in general of a sealed tubular envelope 24 that has an opaque 3coating 26 at one end and a base 28 at the other end. The base isprovided with a keyed center post 30 to insure that the lamp is properlyinserted into its socket. Sealed into the envelope is an ellipsoidalmetal reflector 34 and a concentrated filament 38 of suitable refractorymetal such as tungsten or the like.

The filament 38 is supported at or proximate the focal point of thereflector 34 by a pair of spaced lead wires 35 and 36 which, in turn,are attached to but insulated from the reflector by a ceramic insulator37 that is seated in a suitable opening in the reflector. The aforesaidelements comprise a separate integral assembly 32 which will hereafterbe referred to as the reflector-filament assembly. This assembly issupported within the envelope by a plurality of support members andconjoined lead-in conductors that pass through the wafer type stemsealed to the end of the envelope and serve as pin terminals forenergizing the filament. The reflector 34 can be fabricated from glasscoated with silver or the like, or it can be stamped from metal andsubsequently refiectorized as in the case here illustrated.

A detailed illustration and description of a projection lamp of theaforesaid design is set forth in US. Patent No. 2,980,818, issued Apr.18, 1961. a

As shown more particularly in FIG. 2, the filament 38 is of coiled-coilconstruction and is provided at each end with uncoiled leg sections 39which are attached as by welding or the like to the spaced lead wires 35and 36. The position of the coiled body portion of the filament relativeto the focal point of the ellipsoidal reflector 34 can, accordingly, bevery readily altered by bending the tips of the lead wires or theadjoining uncoiled leg sections of the filament before thereflector-filament assembly 32 is attached to its support wires andsealed into the envelope.

A preferred form of apparatus 40 for practicing the present invention isshown in FIG. 3, which apparatus comprises an elongated base plate orchassis 42 having a longitudinally extending track such as a groove orchannel 43 in its upper face. A jig 44 for holding thereflector-filament assembly 32 in predetermined position relative to thechannel is located at one end of the chassis and a carrier 52 is locatedat the other end. The bottoms of the jig 44 and carrier 52 are contouredto interfit with the channel 43 so that both of these members aremovable toward and away from each other along a predetermined axisdefined by the channel 43. The holding jig 44 can be locked at a givenposition along the channel by suit able means such as a set screw 57(see FIG. 4). The carrier 52 is also made adjustable as by providing anelongated slot 54 in its central portion and a set screw 56 that fitsloosely within the slot and engages a threaded hole in the chassis.

The restricted light beams required by the invention are obtained byattaching a pair of suitable light sources 63 and 64 to the carrier 52by adjustable arms 61 and 62. The light sources are located adjacent thepath of movement of the carrier on opposite sides thereof and are soconstructed as to direct a restricted beam of light toward the holdingjig 44 at predetermined angles with respect to the channel 43. The endof the carrier nearest the jig is suitably slotted and supports a screen58 of ground glass or the like upon which is inscribed a suitablereference mark such as a rectangular box 60.

To facilitate the loading and unloading of the reflectorfilamentassembly 32 and lock it in a predetermined position with respect to thechannel 43, screen 58 and light sources 63 and 64, the holding jig 44 isprovided with two upstanding clamping jaws 45 and 46 the inwardlydisposed work faces whereof are spaced and contoured nestingly toreceive the circular peripheral edges of the reflector 34, as shown inFIGS. 3 and 4. Since oppositely disposed segments of the reflector arecut away to permit the reflector-filament assembly 32 to be insertedinto the tubular envelope 24, this arrangement insures that the assemblyis automatically oriented in the proper position when it is placedbetween the jaws.

The clamping jaw 46 is rotatable about an axis perpendicular to thelongitudinal axis of the chassis 42 so as to be swingable toward andaway from the other clamping jaw 45 by means of a lever 48, as shown bythe dotted line portions of FIG. 4. The lever 48 is preferably connectedby a spring 49 to a pin 50 located on the lower part of the jig. Themovable jaw 46 is thus maintained by the action of the spring in seatedengagement with the edge of the reflector 34 thereby positively locatingthe reflector-filament assembly in the holding jig 44.

As shown in FIGS. 4 and 5, one convenient arrangement for rotatablycoupling the jaw 46 to the jig 44 is to provide the jaw with a laterallyprojecting arm 47 the end portion whereof fits into an opening in thejig and is suitably apertured to receive and pivot around a pair of pins53 and 54 (FIG. 5) seated in the jig. The lever 48 is fastened to themovable jaw 46 in any suitable manner as by threading the end of thelever and screwing it into a threaded aperture provided in the arm 47,as illustrated most particularly in FIG. 5.

As is shown in FIGS. 3 and 4, the work faces of the clamping jaws 45 and46 are cut away to provide a groove 51 and a projecting lip 53 threatwhich define a cavity that nestingly receives the circular peripheraledges of the reflector 34. Hence, when the reflector-filament assembly32 is inserted into the holding jig 44, the positive seating action ofthe jaws locks the assembly in such a position that the axis ofrevolution of the reflector is parallel to the axis of the channel 43and the filament 38 is perpendicular to the latter. Thus, in the case ofan ellipsoidal reflector 34 of the type here shown, when the beams fromthe light sources 63 and 64 are oriented so that the beam axes intersectat the first focal point of the reflector and the carrier 52 is soadjusted so that the screen 58 is located a fixed distance d therefromat the second focal point of the reflector (see FIG. 4), the reflectedshadows of the filament 38 projected onto the screen by the reflectorwill coincide and a single shadow will appear in the reference box 60,as shown in FIG. 3, if the filament is located precisely at the firstfocal point.

The above-described arrangement is diagrammatically illustrated in FIG.6. As there shown, the coiled filament 38 is located at the first focalpoint 7; of the ellipsoidal reflector 34 and the screen 58 is located afixed distance d from the plane a-a tangent to the edges of thereflector such that the screen is located at the second focal point fThe reflector is of such a depth in this particular case that the focalpoint f is outside the reflector and is spaced from the cutoff plane aaa predetermined distance d The light beams B B are aimed so that thebeam axes intersect approximately at the first focal point f therebycausing the two reflected shadows of the filament to merge and overlapat the second focal point f Under these conditions a single shadow S ofthe filament will appear within the reference box 60 inscribed on thescreen 58 indicating that the filament is located precisely at the firstfocal point h of the reflector.

If the filament 38 is located at a point closer to the reflector 34 thanthe first focal point 1; and on the reflector axis, then the reflectedshadows of the filament will overlap at some point C located aconsiderable distance beyond the screen 58. This condition isillustrated in FIG. 8 and results in two shadows S and S on the screen.As shown in FIG. 9, these shadows will be in line with the reference box60 but spaced equal distances on either side thereof.

Should the filament 38 be located beyond the first focal point f at apoint on the reflector axis, then the reflected filament shadows willoverlap at a point C' located somewhere between the screen 58 and thefilament. This situation is shown in FIG. 10 and, since the reflectedlight beams diverge after intersecting, it also results in theappearance of two shadows S and S on the screen. As will be noted inFIG. 11, the orientation of the reflected shadows relative to thereference box 60 on the screen corresponds to that which results whenthe filament is located closer to the reflector than the first focalpoint f as in the case illustrated in FIGS. 8 and 9. However, becausethe reflected light beams intersect and then diverge the position of thereflected shadows on the screen are inverted in this instance.

In the event the filament 38 is located at a point beyond the firstfocal point f and to the right thereof, as is shown in FIG. 12, then thereflected shadows S and S of the filament will be shifted to the left ofthe screen 58 when the latter is viewed from the rear. If the filamentwere in line with beam B and the focal point f as illustrated, theshadow S would appear at the left-hand edge of the screen and the othershadow S would appear inside the reference box 60, as shown in FIG. 13.

Since the screen intercepts the reflected light beams and shadows of thefilament, the deviation of the filament shadows from the point ofreference on the screen is in the reverse direction from that of theactual misalignment of the filament with respect to the focal point ofthe reflector. For example, if the filament is located to the right ofthe focal point f then the reflected shadows of the filament on thescreen will be shifted to the left of the reference mark, as in the caseillustrated in FIGS. 12 and 13. Hence, the filament must be moved to theleft toward f and back toward the reflector to produce a resultant shiftto the right and convergence of the filament shadows on the screen. Thedirection in which the filament must be moved to correct for eachmisalignment is indicated by small arrows in each of the figures.

Thus, with a little experience an operator simply by observing thelocation and movement of the reflected shadows of the filament on thescreen can very quickly position the filament precisely at the focalpoint f Since the beam axes intersect at the focal point fr, it shouldbe noted that the beams themselves overlap for a considerable distancebeyond the focal point. Hence, the filament can also be very readilypositioned accurately at any point offset and proximate the focal pointf that lies within the region of beam overlap.

The position of the filament 38 is preferably adjusted by bending theuncoiled leg sections adjacent the lead wires. However, the adjustmentmay also be made by bending the lead wires themselves, particularly ifthe filament must be moved a considerable distance.

The principles of this invention are also applicable to other types ofcurved reflector surfaces. For example, the same advantageous resultscan be obtained with parabolic reflectors of the type used in sealedbeam automotive lamps. Since light rays passing through the focal pointof parabolic reflectors are reflected in a direction parallel to thereflector axis and are not focused at a second focal point as in thecase of an elliptical reflector, the screen in this case must be madelarger or two separate screens separated a fixed distance apart must beused in order to intercept the more widely spaced reflected shadows ofthe filament. In FIG. 14 there is shown one suitable arrangement forchecking and adjusting the position of a filament 38 with respect to thefocal point 1 of a parabolic reflector 34a wherein a wide screen 58ahaving two reference boxes 61 and 62 separated a predetermined distanced;., apart is used. When the filament 38 is located precisely at thefocal point 1 of the reflector, as here illustrated, the reflectedfilament shadows S and S will be centered within the respectivereference boxes as shown in FIG. 15.

However, if the filament is located between the reflector and its focalpoint 1 and on axis of the reflector, as in the case shown in FIG. 16,then the reflected filament shadows S and S will be shifted outwardlyapproximately equal distances toward the sides of the screen. Theshadows will, accordingly, be located outside the boxes 61, 62 proximatethe outer edges of the screen as shown in FIG. 17.

Should the filament be on the reflector axis but between the focal pointand the screen, as illustrated in FIG. 18, then the reflected filamentshadows S and S will be shifted toward one another and be locatedapproximately equal distances inwardly of and in line with the referencemarks on the screen, as is illustrated in FIG. 19.

In the event the filament 38 is located to the right of the reflectoraxis between the focal point I and the screen 58a then the reflectedfilament shadow S produced by the light beam B will be shifted towardthe left of the screen. If in this case the filament were located on theaxis of the light beam B as shown in FIG. 20, then the reflected shadowS produced by this beam will be centered in the left-hand box 61 on thescreen whereas the reflected shadow S produced by beam B will be l0-cated somewhere between the reference marks, as depicted in FIG. 21.

In order to maintain the width of the filament shadow as near aspossible to the width of the actual filament the beams B B arepreferably aimed so that the angle between each of the beams and thereflector axis is in each case not more than about 45 It will be obviousfrom the foregoing that the present invention can be employed to checkthe alignment of an element with respect to curved reflector surfaces ofvarious configurations and that one instead of two beams of light can beused. By observing the orientation of the reflected shadow of theelement with respect to a preselected reference point on a screenlocated at a predetermined distance and position from the reflectingsurface, it is possible to locate the element with the same degre ofaccuracy as when two beams are used. Also, the element can remainstationary and the reflector moved t obtain the desired alignment.

It will also be obvious to those skilled in the art that other forms ofradiant energy other than light beams can also be employed to project areflected shadow of the element onto a screen. For example, restrictedbeams of ultraviolet rays. X-rays, infrared rays or gamma rays and otherforms of electromagnetic radiation can be employed, providing thereflecting surface reflects such energy and the element absorbs or has amuch lower coefficient of reflectivity than the reflecting surface forthe particular type of energy involved. Of course, the screen must be ofa type that detects or is responsive to the reflected radiant energy soas to permit the position of the reflected shadow of the element to beobserved or otherwise determined. For example, in the case of UV beamsthe viewing screen can comprise a surface that is coated with a phosphorthat is responsive to UV and will thus visibly indicate the location ofthe reflected shadow or shadows.

It will be apparent from the foregoing that the objects of the inventionhave been achieved in that an inexpensive simple apparatus foraccurately prefocusing the light source and integral reflector of anelectric lamp on a production line basis has been provided.

While one form of prefocusing apparatus has been described, it will beappreciated that various structural modifications can be made thereinwithout departing from the spirit and scope of the invention. Forexample, the positions of the screens and radiant energy sources in anyof the arrangements set forth above can be reversed to obtain the sameoptical effects and rapid indication of misalignment as that described.

I claim as my invention:

1. Apparatus for determining the position of a component relative to aconcave reflector to which it is attached, said apparatus comprising; achassis having a longitudinal axis, holding means on said chassis forholding said reflector in a position such that its concave reflectivesurface faces toward the longitudinal axis of said chassis, means onsaid chassis for directing two beams of radiant energy toward saidholding means at an angle of incidence relative to the concavereflective surface of a reflector placed in said holding means and alongpaths such that the beam axes pass through the component attached tosaid reflector, and a screen on said chassis at a location relative tosaid holding means, the longitudinal axis of said chassis, and said beamaxes that it intercepts the beams of radiant energy reflected by thereflector placed in said holding means and indicates the position of thecomponent relative to said reflector by the location of the projectedshadows of said component relative to a reference area on said screen.

2. Apparatus for checking the position of a concentrated filamentrelative to the focal point of a concave reflector to which it isattached and indicating the degree of misalignment, if any, of saidfilament from a preselected position, said apparatus comprising; anelongated chassis having a longitudinal axis, a holder at one end ofsaid chassis having portions contoured to nestingly receive and providea seat for preselected portions of said reflector sothat the reflectoraxis is parallel to said longitudinal axis, a carrier attached to saidchassis, light source means on said carrier for directing two beams oflight onto the concave surface of the reflector in said holding meansfrom locations adjacent to but on opposite sides of the axis of saidreflector and along axes that pass through the filament attached to saidreflector, and a screen on said carrier at a location relative to saidholding means and beam axes that it intercepts the reflected light beamsfrom said reflector and, by means of the shadows of the filamentprojected onto a reference area on said screen, indicates the positionof the filament relative to the reflector.

3. The apparatus set forth in claim 2 wherein; and holding meanscomprises a jig having two upstanding clamping jaws that are spaced andcontoured to grip the peripheral edges of said reflector and lock it inposition on said chassis, and said carrier is movable along a channel insaid chassis that extends along the direction of the longitudinal axisthereof so that the spacing between said carrier and jig can be varied.

4. The apparatus set forth in claim 3 wherein one of said clamping jawsis rotatable about an axis that is normal to the longitudinal axis ofsaid chassisand is thereby swingable toward and away from the other ofsaid clamping jaws.

5. The apparatus set forth in claim 3 wherein said light source meanscomprises a pair of light sources that are attached to said carrier byadjustable arms.

6. The apparatus set forth in claim 3 wherein; said jig is also movablealong said channel, said clamping jaws are so disposed that the axis ofa reflector locked therein is substantially parallel with the channel insaid chassis, said screen is located at the end of said carrierproximate said jig, and said light source means comprises a pair oflight sources that are attached to the other end of said carrier bymeans which permit said light sources to be aimed at said jig fromopposite sides of said channel.

References Cited UNITED STATES PATENTS 2/1928 Cronjaeger. 3/1929 Bohner88-14 US. Cl. X.R.

